1. Field of the Invention
The invention relates to an apparatus for recording a first and a second digital information signal in tracks on a record carrier, the first and second digital information signals being information signals comprising subsequent packets of information, the apparatus comprising:
input means for receiving the first and second digital information signals,
signal processing means for processing the first and second digital information signals into a first recording signal and a first trick play signal, respectively, suitable for recording in the tracks on said record carrier, the signal processing means being adapted to generate sync blocks of information, each sync block comprising a first block section which comprises a synchronization signal, and a second block section which comprises a number of information bytes, the signal processing means being further adapted to store, each time, the information included in x transport packets of the first digital information signal in the second block sections of y first sync blocks, the second block section of at least the first sync block of the group of y first sync blocks comprising a third block section for storing a time stamp, the signal processing means being further adapted to store, each time, the information included in x transport packets of the second digital information signal in the second block sections of y second sync blocks, the second block section of at least the first sync block of the group of y second sync blocks comprising a third block section for storing a time stamp,
time stamp generator means for generating a time stamp, the time stamp generator means comprising counter means adapted to generate subsequent cycles of count values, the signal processing means being adapted to store a time stamp, generated by the time stamp generator means, for a corresponding packet in the third block section of a sync block, and being adapted to combine the first and second sync blocks into a composite signal, and
writing means for writing the composite signal in the tracks at a predetermined recording speed of the record carrier, the writing means comprising a first and a second write head positioned on a rotatable head drum, said first write head having a first azimuth angle and said second write head having a second azimuth angle, which is different from the first azimuth angle, the first digital information signal being meant for reproduction in a reproduction apparatus at a reproduction speed which is equal the recording speed, the second digital information signal being meant for reproduction at a trick play speed which is equal to n1 times said recording speed, where n1 is a positive integer larger than 1.
2. Description of the Related Art
Such a recording apparatus is known from U.S. Pat. No. 5,751,889, corresponding to International Patent Application No. WO 95/28061, document D4 in the List of Related Documents.
The known apparatus takes the form of a digital video recorder for recording a digital video signal. The digital video signal may be in the form of an MPEG-encoded video signal, in which packets of information of the digital video signal are included in the serial data stream of the MPEG-encoded video signal. In addition to such MPEG-encoded video signal, a trick play signal can be recorded in the tracks on the record carrier. This trick play signal can be the same video signal, but reproduced at a record carrier (trick play) speed which is other than the nominal reproduction speed. Generally, a separate datastream is recorded as the trick play signal on the record carrier for enabling the reproduction at such trick play speed. The trick play signal can be derived from the MPEG-encoded video signal, e.g., by selecting I-frames from the MPEG-encoded video signal.
This trick play signal, however, need not necessarily be a trick play signal that has a relationship with the MPEG-encoded video signal, but can be a completely different signal. But, in the same way as the MPEG-encoded digital video signal, the serial datastream of the trick play signal comprises packets of information of the trick play signal.
The document mentioned above describes the inclusion of time stamps in the packets in all the serial datastreams recorded on the record carrier, in order to enable a correct regeneration of the serial datastream of packets, with the correct mutual timing relationships between the subsequent packets in the serial datastream, so that a correct decoding in an MPEG decoder will be possible. In order to realize this, the reproducing apparatus for reproducing an MPEG-encoded information signal includes a buffer memory in which the packets read from the record carrier are stored. The packets are retrieved from this buffer memory in response to the time stamps included in each packet, for further processing in the MPEG decoder.
It is an object of the invention to provide a recording apparatus for recording one or more trick play signals, which is capable of generating all the time stamps for the packets in those signals.
The recording apparatus in accordance with the invention is characterized in that the time stamp generator means comprises first counter means for generating subsequent cycles of first count values so as to supply time stamps for said first digital information signal, and second counter means for generating subsequent cycles of second count values so as to supply time stamps for said second digital information signal, said first counter means supplying said first count values at a first rate, and said second counter means supplying said second count values at a second rate, which equals said first rate divided by n1.
The invention is based on the following recognition. During reproduction in said trick play reproduction mode, it is desired to obtain a trick play datastream with a certain bit-rate, this bit-rate being the same as the bit-rate during normal play. Reproducing trick play at n1 times the nominal recording speed means that the bit-rate of the data read from the record carrier is multiplied by n1 compared to the bit-rate of the data during reproduction at nominal play. Therefore, in order to make this bit-rate equal in both reproduction modes, this requires a kind of xe2x80x98slow motion recordingxe2x80x99 during the recording of the trick play data. This reflects itself in a lower clock frequency for the counters for generating the time stamps for the trick play data, where the ratio of the clock frequencies equals n1.
The same reasoning is valid for the trick play signals for other trick play reproduction modes at other speeds of the record carrier.
Further, for a speed xe2x88x92n1 times the recording speed, the count values are generated in the reverse direction.